title: Volumetric-modulated arc therapy in head and neck radiotherapy: a planning comparison using simultaneous integrated boost for nasopharynx and oropharynx carcinoma.
abstract: OBJECTIVE
  Volumetric-modulated arc therapy (VMAT) allows rapid delivery of radiotherapy. The aim of this planning study was to evaluate VMAT and dynamic intensity-modulated radiotherapy (IMRT) using a simultaneous integrated boost technique
  
  
  METHODS
  Planning computed tomography data from 10 patients with locoregionally advanced oropharynx or nasopharynx carcinoma were selected. The prescription dose was 70, 63 and 56Gy to the high-dose, intermediate-dose and low-dose planning target volume (PTV), respectively, and planning parameters were according to Radiation Therapy Oncology Group IMRT protocols. VMAT and IMRT plans were calculated, and dose-volume histograms were created for plan evaluation and comparison.
  
  
  RESULTS
  Clinically acceptable plans were achieved for both IMRT and VMAT plans, although IMRT plans typically required three times the number of monitor units. The coverage of 95% of the PTV70 was between 96 and 100% of the prescribed dose for IMRT plans and 100% for all VMAT plans. There was a trend of improved dose conformity for IMRT plans. Both IMRT and VMAT achieved acceptable plans in terms of sparing of the spinal cord and brainstem. Contralateral parotid sparing was improved with VMAT, with a mean dose of 25.08Gy (range 21.35-30.02Gy) for oropharynx and 31.37Gy (range 23.47-35.52Gy) for nasopharynx cases.
  
  
  CONCLUSIONS
  Simultaneous integrated boost VMAT achieved comparable plans to dynamic IMRT in complex head and neck cases and used two-thirds less monitor units.
authors.affiliation: Radiation Oncology Department, Northern Sydney Cancer Centre, St Leonards, New South Wales, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Johnston
authors.forename: S
authors.initials: S
authors.lastname: Clifford
authors.forename: R
authors.initials: R
authors.lastname: Bromley
authors.forename: M
authors.initials: M
authors.lastname: Back
authors.forename: L
authors.initials: L
authors.lastname: Oliver
authors.forename: T
authors.initials: T
authors.lastname: Eade
mesh_terms: D002277:Carcinoma; D006801:Humans; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009959:Oropharyngeal Neoplasms / Q000532:radiotherapy*; D016544:Patient Simulation; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated